1. Technical Field
This invention pertains to passenger conveying devices having handrails in general, and to handrail drives for passenger conveying devices in particular.
2. Background Art
Passenger conveying devices such as escalators and moving walkways are a well known means for conveying passengers from one point to another. Typically, passengers enter the device through a landing and step on to a moving step (or pallet, or belt, etc.). The moving step conveys the passenger(s) along at a relatively constant speed until he or she reaches the opposite landing. The passenger subsequently steps off the moving step and on to a stationary floorplate in the opposite landing, and is thereafter free to go as he or she pleases.
For safety reasons, it is well known in the art that a pair of handrails may be provided on both sides of the steps. The handrails facilitate the passengers ride, especially in the transition areas where the passenger is entering and exiting the device. The handrails typically travel a closed loop about a balustrade assembly, including a return trip within the base of the balustrade. The balustrade assemblies guide and support the handrail.
A handrail drive, enclosed within the passenger conveyor, drives the handrail about the guided path at approximately the same speed as the moving steps. A person of skill in the art will recognize that there are many handrail drive embodiments known. Most drives impart motion to the handrail by applying frictional force to the handrail, sometimes referred to as "pinching" the handrail within a nip point. U.S. Pat. No. 5,125,494 to Nurnberg et al. discloses that a handrail may be driven by pinching it between a belt and an idler pulley. U.S. Pat. No. 3,779,360 to Taher et al. discloses that a handrail may be driven by pinching it between a pressure roller and a traction roller.
A person of skill in the art will recognize that it is known to use polyurethane rollers in those embodiment using rollers. Polyurethane rollers provide several advantages including: the minimization of handrail discoloration, also known as "marking"; the minimization of scratching of the outer surface of the handrail; and the provision of a coefficient of friction sufficient to drive the handrail.
A person of skill in the art will recognize that indentations within the outer surface of the handrail often occur when a passenger conveying device is idled, for example, during weekends or non-peak hours. Indeed, many passenger conveying devices now may include controls which allow the device to be operated intermittently, thereby exacerbating the problem. The indentations occur because the handrail drive pinches a section of idled handrail for an extended period of time. It would be advantageous to minimize the magnitude of the indentations within the handrail and thereby decrease the amount of time it takes the elastic handrail to return to its normal profile.